Determine how many solutions exist for the system of equations. ${x+y = 3}$ ${-18x-3y = -6}$
Answer: Convert both equations to slope-intercept form: ${x+y = 3}$ $x{-x} + y = 3{-x}$ $y = 3-x$ ${y = -x+3}$ ${-18x-3y = -6}$ $-18x{+18x} - 3y = -6{+18x}$ $-3y = -6+18x$ $y = 2-6x$ ${y = -6x+2}$ Just by looking at both equations in slope-intercept form, what can you determine? ${y = -x+3}$ ${y = -6x+2}$ The linear equations have different slopes. ${1}$ ${2}$ ${3}$ ${4}$ ${5}$ ${6}$ ${7}$ ${8}$ ${9}$ ${\llap{-}2}$ ${\llap{-}3}$ ${\llap{-}4}$ ${\llap{-}5}$ ${\llap{-}6}$ ${\llap{-}7}$ ${\llap{-}8}$ ${\llap{-}9}$ ${1}$ ${2}$ ${3}$ ${4}$ ${5}$ ${6}$ ${7}$ ${8}$ ${9}$ ${\llap{-}2}$ ${\llap{-}3}$ ${\llap{-}4}$ ${\llap{-}5}$ ${\llap{-}6}$ ${\llap{-}7}$ ${\llap{-}8}$ ${\llap{-}9}$ When two equations have different slopes, the lines will intersect once with one solution.